LIGHT EMITTING STRUCTURE AND SEMICONDUCTOR LIGHT EMITTING ELEMENT HAVING THE SAME
A light emitting structure includes an N-type semiconductor layer, a P-type semiconductor layer, a light emitting layer, and a stress regulation layer. The light emitting layer is formed between the N-type semiconductor layer and the P-type semiconductor layer. The stress regulation layer is formed between the N-type semiconductor layer and the light emitting layer. The stress regulation layer comprises a plurality of pairs of AlxIn(1-x)GaN and AlyIn(1-y)GaN layers stacked with each other, wherein 0<x<1, 0≦y<1, thickness of the stress regulation layer is between 50 nanometer and 500 nanometer, and x≠y.
1. Field of the Invention
The present invention relates to a light emitting structure, and more particularly, to a light emitting structure having a stress regulation layer.
2. Description of the Prior Art
Since light emitting diodes (LEDs) have advantages of long service life, small size and low power consumption, the light emitting diodes are widely used in various kinds of illumination devices and display devices. Generally, the light emitting diode has a light emitting structure comprising an N type semiconductor layer, a P type semiconductor layer and a light emitting layer. The light emitting layer comprises a plurality of pairs of two specific materials stacked on each other, to be formed on the N type semiconductor layer.
However, in the light emitting structure of the light emitting diode of the prior art, The light emitting layer may have an uneven surface structure or dislocation due to huge differences in atomic arrangement direction and atomic size between the light emitting layer and the N type semiconductor layer, such that the light emitting layer has residual stress inside. The residual stress may easily cause occurrence of defect in the light emitting structure, so as to seriously affect light emission efficiency and production yield of the light emitting diode.
SUMMARY OF THE INVENTIONThe present invention provides a light emitting structure, comprising an N type semiconductor layer, a P type semiconductor layer, a light emitting layer and a stress regulation layer. The light emitting layer is formed between the N type semiconductor layer and the P type semiconductor layer. The stress regulation layer is formed between the N type semiconductor layer and the light emitting layer. The stress regulation layer comprises a plurality of pairs of an AlxIn(1-x)GaN layer and an AlyIn(1-y)GaN layer stacked on each other, wherein 0<x<1, 0≦y<1, x≠y, and thickness of the stress regulation layer is between 50 nm and 500 nm.
The present invention further provides a semiconductor light emitting element, comprising a substrate, a light emitting structure, an N type electrode and a P type electrode arranged. The light emitting structure is arranged on the substrate. The light emitting structure comprises an N type semiconductor layer, a P type semiconductor layer, a light emitting layer and a stress regulation layer. The light emitting layer is formed between the N type semiconductor layer and the P type semiconductor layer. The stress regulation layer is formed between the N type semiconductor layer and the light emitting layer. The stress regulation layer comprises a plurality of pairs of an AlxIn(1-x)GaN layer and an AlyIn(1-y)GaN layer stacked on each other, wherein 0<x<1, 0≦y<1, x≠y, and thickness of the stress regulation layer is between 50 nm and 500 nm. The N type electrode is arranged on the N type semiconductor layer. The P type electrode is arranged on the P type semiconductor layer.
In contrast to the prior art, the light emitting structure and the semiconductor light emitting element of the present invention comprise stress regulation layers for improving surface flatness of the light emitting layer during formation, in order to regulate stress generated during the formation of the light emitting layer. Therefore, the light emitting structure and the semiconductor light emitting element of the present invention have better light emission efficiency and production yields.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Please refer to
According to the above arrangement, since the stress regulation layer 120 is made of four-member materials of AlxIn(1-x)GaN and AlyIn(1-y)GaN, stress effect between AlxIn(1-x)GaN and AlyIn(1-y)GaN is smaller. Therefore, when the light emitting layer 130 grows on the stress regulation layer 120, stress generated during the formation of the light emitting layer 130 can be regulated by the stress regulation layer 120, so as to improve light emission efficiency and production yield of the light emitting structure 100.
In the above embodiment, thickness of the stress regulation layer 120 is between 50 nm and 500 nm, and the stress regulation layer 120 comprises 3 to 30 pairs of the AlxIn(1-x)GaN layer 122 and the AlyIn(1-y)GaN layer 124 stacked on each other. When the thickness of the stress regulation layer 120 is within the above range, a composition ratio of the stress regulation layer 120 can be preciously controlled during an epitaxy process, the light emitting layer 130 growing on the stress regulation layer 120 has better surface flatness. If the stress regulation layer 120 is too thick, an electron transfer path becomes longer, so as to increase possibility of the electron being restrained by defects, such that the light emission efficiency is affected, and stress accumulation is increased. Preferably, the thickness of the stress regulation layer 120 is between 150 nm and 200 nm, and the stress regulation layer 120 comprises 15 to 20 pairs of the AlxIn(1-x)GaN layer 122 and the AlyIn(1-y)GaN layer 124, so as to match better with the light emitting layer 130. A ratio of thickness of the AlxIn(1-x)GaN layer 122 to thickness of the AlyIn(1-y)GaN layer 124 is between 2 and 4, and thickness of each pair of the AlxIn(1-x)GaN layer 122 and the AlyIn(1-y)GaN layer 124 is between 2 nm and 15 nm, such that the stress regulation layer 120 can provide better stress regulation effect. For example, the thickness of the AlxIn(1-x)GaN layer 122 is 7.5 nm, and the thickness of the AlyIn(1-y)GaN layer 124 is 2.5 nm, the stress regulation layer 120 can provide better stress regulation effect to the light emitting layer 130 according to the above thickness ratio. In addition, silicon doping concentrations of the AlxIn(1-x)GaN layer 122 and the AlyIn(1-y)GaN layer 124 are between 1×1017 cm−3 and 3×1018 cm−3, in order to increase crystallinity and conductivity of the stress regulation layer 120.
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Similarly, when forming the semiconductor light emitting element 300 of the present invention, the stress regulation layer 120 has better surface flatness. Therefore, when the light emitting layer 130 is forming on the stress regulation layer 120, stress generated during formation of the light emitting layer 130 can be regulated by the stress regulation layer 120, so as to improve light emission efficiency and production yield of the semiconductor light emitting element 300 of the present invention.
In contrast to the prior art, the light emitting structure and the semiconductor light emitting element of the present invention comprise stress regulation layers for improving surface flatness of the light emitting layer during formation, in order to regulate stress generated during the formation of the light emitting layer. Therefore, the light emitting structure and the semiconductor light emitting element of the present invention have better light emission efficiency and production yields.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A light emitting structure, comprising:
- an N type semiconductor layer;
- a P type semiconductor layer;
- a light emitting layer formed between the N type semiconductor layer and the P type semiconductor layer; and
- a stress regulation layer formed between the N type semiconductor layer and the light emitting layer, the stress regulation layer comprising a plurality of pairs of an AlxIn(1-x)GaN layer and an AlyIn(1-y)GaN layer stacked on each other, wherein 0<x<1, 0≦y<1, x≠y, and thickness of the stress regulation layer is between 50 nm and 500 nm.
2. The light emitting structure of claim 1, wherein the light emitting layer comprises a plurality of pairs of an InmGa(1-m)N layer and an InnGa(1-n)N layer stacked on each other, wherein m>n, and n≧0.
3. The light emitting structure of claim 1, wherein the stress regulation layer comprises 3 to 30 pairs of the AlxIn(1-x)GaN layer and the AlyIn(1-y)GaN layer stacked on each other.
4. The light emitting structure of claim 1, wherein in a pair of the AlxIn(1-x)GaN layer and the AlyIn(1-y)GaN layer, the AlxIn(1-x)GaN layer is closer to the N type semiconductor layer, the AlyIn(1-y)GaN layer is closer to the light emitting layer, and x>y.
5. The light emitting structure of claim 4, wherein in the pair of the AlxIn(1-x)GaN layer and the AlyIn(1-y)GaN layer, 0<y<x<1.
6. The light emitting structure of claim 5, wherein a ratio of thickness of the AlxIn(1-x)GaN layer to thickness of the AlyIn(1-y)GaN layer is between 2 and 4.
7. The light emitting structure of claim 1, wherein silicon doping concentrations of the AlxIn(1-x)GaN layer and the AlyIn(1-y)GaN layer are between 1×1017 cm−3 and 3×1018 cm−3.
8. The light emitting structure of claim 1, wherein thickness of each pair of the AlxIn(1-x)GaN layer and the AlyIn(1-y)GaN layer is between 2 nm and 15 nm.
9. A semiconductor light emitting element, comprising:
- a substrate;
- a light emitting structure of claim 1 arranged on the substrate;
- an N type electrode arranged on the N type semiconductor layer; and
- a P type electrode arranged on the P type semiconductor layer.
Type: Application
Filed: Aug 14, 2014
Publication Date: Feb 19, 2015
Inventors: Jyun-De Wu (Tainan City), Shen-Jie Wang (New Taipei City)
Application Number: 14/459,335
International Classification: H01L 33/12 (20060101); H01L 33/00 (20060101); H01L 33/32 (20060101);